California Gull, Larus californicus

California Gulls in breeding plumage, pictured above
and in the two below, show a red gonydeal spot (the spot
on the bill), a red gape (corner of the mouth), and red
orbital ring (the bare skin around the eye). In the last
few decades, thousands of these birds have come to nest in
southern San Francisco Bay, where previously they were
rare in breeding season. Most California Gulls nest on
lakes in the interior west, most famously the Great Salt
Lake, where their arrival in the summer of 1848 and
subsequent foraging demolition of a plague of plant-eating
insects was seen by the Mormons as a divine intervention
to rescue their new settlement there. As a result of the
"Miracle of the Gulls," the California Gull is the state
bird of Utah, commemorated by the Seagull Monument in Salt
Lake City's Temple Square.

Above and below, adult California Gulls in their
non-breeding plumage; they winter in large numbers along
the Pacific Coast. Their gonydeal spot is usually a
mixture of black and red.

Above, a California Gull in third-cycle winter plumage
-- similar to adult plumage, but recognizable here by the
absence of red on the bill. Below, another third cycle
bird (left) fighting with a non-breeding adult; this one
has red in the bill, but the dark feathers in the tail
identify it as sub-adult, by contrast to the all-white
tail of the adults further above.

Above and below, California Gulls at the end of their
first cycle, in the summer of their second calendar year;
the bird above is more worn and faded, the one below
retains more of the dark feather tips that create the
characteristic brown first-year appearance.

Above, a first-cycle California Gull in winter; below,
a bird in August, still in its juvenal plumage.